1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
|
/*
* Interface to libgsm for gsm encoding/decoding
* Copyright (c) 2005 Alban Bedel <albeu@free.fr>
* Copyright (c) 2006, 2007 Michel Bardiaux <mbardiaux@mediaxim.be>
*
* This file is part of FFmpeg.
*
* FFmpeg is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* FFmpeg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file libgsm.c
* Interface to libgsm for gsm encoding/decoding
*/
// The idiosyncrasies of GSM-in-WAV are explained at http://kbs.cs.tu-berlin.de/~jutta/toast.html
#include "avcodec.h"
#include <gsm.h>
// gsm.h misses some essential constants
#define GSM_BLOCK_SIZE 33
#define GSM_MS_BLOCK_SIZE 65
#define GSM_FRAME_SIZE 160
static av_cold int libgsm_init(AVCodecContext *avctx) {
if (avctx->channels > 1 || avctx->sample_rate != 8000 || avctx->bit_rate != 13000)
return -1;
avctx->priv_data = gsm_create();
switch(avctx->codec_id) {
case CODEC_ID_GSM:
avctx->frame_size = GSM_FRAME_SIZE;
avctx->block_align = GSM_BLOCK_SIZE;
break;
case CODEC_ID_GSM_MS: {
int one = 1;
gsm_option(avctx->priv_data, GSM_OPT_WAV49, &one);
avctx->frame_size = 2*GSM_FRAME_SIZE;
avctx->block_align = GSM_MS_BLOCK_SIZE;
}
}
avctx->coded_frame= avcodec_alloc_frame();
avctx->coded_frame->key_frame= 1;
return 0;
}
static av_cold int libgsm_close(AVCodecContext *avctx) {
gsm_destroy(avctx->priv_data);
avctx->priv_data = NULL;
return 0;
}
static int libgsm_encode_frame(AVCodecContext *avctx,
unsigned char *frame, int buf_size, void *data) {
// we need a full block
if(buf_size < avctx->block_align) return 0;
switch(avctx->codec_id) {
case CODEC_ID_GSM:
gsm_encode(avctx->priv_data,data,frame);
break;
case CODEC_ID_GSM_MS:
gsm_encode(avctx->priv_data,data,frame);
gsm_encode(avctx->priv_data,((short*)data)+GSM_FRAME_SIZE,frame+32);
}
return avctx->block_align;
}
AVCodec libgsm_encoder = {
"libgsm",
CODEC_TYPE_AUDIO,
CODEC_ID_GSM,
0,
libgsm_init,
libgsm_encode_frame,
libgsm_close,
};
AVCodec libgsm_ms_encoder = {
"libgsm_ms",
CODEC_TYPE_AUDIO,
CODEC_ID_GSM_MS,
0,
libgsm_init,
libgsm_encode_frame,
libgsm_close,
};
static int libgsm_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
uint8_t *buf, int buf_size) {
if(buf_size < avctx->block_align) return 0;
switch(avctx->codec_id) {
case CODEC_ID_GSM:
if(gsm_decode(avctx->priv_data,buf,data)) return -1;
*data_size = GSM_FRAME_SIZE*sizeof(int16_t);
break;
case CODEC_ID_GSM_MS:
if(gsm_decode(avctx->priv_data,buf,data) ||
gsm_decode(avctx->priv_data,buf+33,((int16_t*)data)+GSM_FRAME_SIZE)) return -1;
*data_size = GSM_FRAME_SIZE*sizeof(int16_t)*2;
}
return avctx->block_align;
}
AVCodec libgsm_decoder = {
"libgsm",
CODEC_TYPE_AUDIO,
CODEC_ID_GSM,
0,
libgsm_init,
NULL,
libgsm_close,
libgsm_decode_frame,
};
AVCodec libgsm_ms_decoder = {
"libgsm_ms",
CODEC_TYPE_AUDIO,
CODEC_ID_GSM_MS,
0,
libgsm_init,
NULL,
libgsm_close,
libgsm_decode_frame,
};
|
